Production of alcohols



Patented Feb. 13, 1940 72,190,501 PRODUCTION OF ALCOHOLS Benjamin T. Brooks,'0ld Greenwich, Conn., assignor to Standard Alcohol Company No Drawing. Application December 4, 1936,

Serial No. 114,135

" 6 Claims; (01. 260-639) This invention relates to improvements in the production of alcohols, In the production of alcohols by treating hydrocarbon mixtures containingolefines, generally of 15-35% olefinecontent, with sulfuric acid, it'isdifficult, or in many cases practically-impossible to produce an acid product containing more than one; mol of com bined olefine to one molof sulfuric acid.

. .Intreating lean gas mixtures, if excess gas is 10 passed through the acid after dialkyl sulfate (diethyl or diisopropyl) begins to be formed-{the dialkyl sulfate may be volatilized in the stream of excess gas, as in sulfating ethylene at low pressures,'or the disulfate may be dissolved in the polymer or tar. formed, as may be the case in sulfatin'g propylene. v

The dialkyl sulfates of the ethylene homologues are freely soluble in hydrocarbon oils, differing from diethyl sulfate' in this respect.

In treating hydrocarbon mixtures containing butenes and/or amylenes, it is common practice to treat with sulfuric acid in proportions -which result essentially in the formation of mono-alkyl sulfate. The acid product formed contains ,mono-alkyl sulfate and uncombined sulfuric acid. Thus, in the manufacture of butyl and amyl alcohols, the proportion of acid used to olefine combined is more than one mol of acid to one mol of combined olefine, resulting, in the uselof 12 to 16 pounds of acid to one gallon of alcohol produced.

Hydrocarbon mixtures made by cracking contain'isomeric butenes and amylenes, together with 60% or more of paraflins, in the C4 and C5 fractions. When the proportion of acid used is diminished in the attempt to produce dialkyl (dibutyl'and diamyl) sulfates, I find that (l) the reactivity of butylor amyl hydrogen sulfate for the normal butenes and amylenes is much less than sulfuric, acid (80 to 93% H2804 commonly used) (2) that the dialkyl (dibutyl and 'diamyl) sulfates are freely soluble in the excess 'naphtha' and to a large extent passes into solution in the naphtha; (3) since polymers are formed, it is impossible to isolate the dialkyl sulfates by distilling or evaporating the excess naphtha, even if it were practical to do so.

According to this invention, it was found that so if acid products are made in the usual way,

containing somewhat less than one mol of combined olefineto one of acid, separated from excess hydrocarbon gas or naphtha and polymer, excess olefine in a concentrated or pure form may then be. combined with the acid product to form an acid reaction product rich in dialkyl sulfate. The acid reaction product thus obtained may be diluted with water to precipitate and remove dialkyl sulfate, or the acid mixture diluted with water may be hydrolyzed 6 and distilled to produce alcohols. This procedure results in less acid used pergallon of alcohol than in former practice.

The olefines used in the second sulfating step may be obtained from any suitable source. In 10 the case of ethylene, the separation of ethylene from accompanying gases, such as hydrogen, methane'and ethane, is expensive. By theprocedure here described, one-half of the ethylene may be extracted from' relatively lean gas, containing up to about 30% ethylene and the second step be carried out with a gas richer in ethylene or with substantially pure ethylene.

In the case of propylene, the first step. may be carried out with a relatively lean gas and 50 the second step with concentrated propylene, as for example the propylene formed in the production of isopropyl etherv fromisopropyl sulfate.

In the case of the butenes and amylenes, an acid containing somewhat less than one mol of 25 butene or amylene to one mol of sulfuric acid may be made by treating suitable fractions of cracked naphtha, the acid product separated then treated with butene or amylene obtained in hydrolyzing and distilling acid alkyl sulfate 39 solutions.

It is possible to separate butenes and amylenes from cracked naphtha fractions containing these olefines by solvent extraction of the naphtha fractions, either in the liquid or gaseous state, since the olefines are more soluble in most organic solvents than the accompanying paraffins. For example, naphtha fractions of C4, C5 and Cs hydrocarbons, preferably close out fractions of hydrocarbons containing the same number of carbon atoms in the molecule, are treated with a solvent, such as liquid S02, acetone, alcohol (ethyl, lsopropyl, butyl, etc.) aniline, phenol, furfural, and the like, in which the olefine is more soluble than the paraffin. fraction thereby contained is substantially free from paraflins, or a fraction containing at most 30% parafiins is used according to this process.

The acid strengths preferred for obtaining an acid product rich in diethyl sulfate are above 90% HzSO4 and temperatures above C.; for propylene acid strengths of 35 to 92% I-I2S04 and temperatures of 15 to 30 C.; for butenes and amylenes the preferred acid concentrations 5 are 80-90% H2SO4 and temperatures of 25 C.

Normal butenes and amylenes are very soluble according to any theory of manufacturing al cohols from olefine hydrocarbons.

I claim:

1. Improvements in the process of manufacturing alcohols which comprisesreacting a hydrocarbon mixture containing lessthan 30% of olefines with an acid hydrolyzing' material to? less than 1 mol of form acid esters containing combined olefin to 1 mcl of the acid, separating any polymers that may be formed and contactin g the residual acid iiquor with a hydrobe mix ure a ing at l t. of olefinr-isj 2 Improvem ents in the process of manufacturing alcohol which comprises contacting a hydrocarbon nixture containing not over of ethylene with sulfuric form'ed contacting the resulting separated acid liquor with a hydrocarbon mixture containing at least 30% of ethylene.

3. Improye ments in the process of manufaccontacting 'a hydrocarbon acid of 90% concen- 80 tration, separating anypolymers: that may be turing ethyl alcohol according to claim 2 in which ethylene is contactedwith 90% sulfuric acid at a temperature above C. and'n'ot over 150 0.. I v e 4. Improvements in the process of manufacturing isopropyl' alcohol which comprises con-,

tacting a hydrocarbon mixture containing not over 30% of propylene withsuliuric acid of 85*, to 92% concentration, separating any polymers that may be formed and contacting the resultin .o ing separated acid liquor withja hydrocarbon mixture containing at least 30% of propylene;

5.-Impro ve m ents in the process of manufacturing secondary butyl alcohol which comprises 30%' of butenes with sulfuric acid of I -90% concentrationinwhich the temperature is maintained at 15 to 25 0., separating any polymers that maybe formed and contacting the, result-t. ing separated acid liquor with a hydrocarbon mixture containing atleast -3 0% of 1butenes.,

6. Improvements containing less than I in the process of manufac-j;

turing isopropyl alcohol which; comprises con-j tacting a hydrocarbon mixture containing not:

over 30% of propylene withsuliuric acid of to 92% concentration, separating any polymers that may be formed, contacting the resultin 1 separated acid liquor with a hydrocarbon mix ture containing at least 30% of propylene, and maintaining a temperature of throughout the process;

BENJAMIN T BROOKS. 

